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Published March 10, 2021 | Published
Journal Article Open

The Neurophysiological Representation of Imagined Somatosensory Percepts in Human Cortex


Intracortical microstimulation (ICMS) in human primary somatosensory cortex (S1) has been used to successfully evoke naturalistic sensations. However, the neurophysiological mechanisms underlying the evoked sensations remain unknown. To understand how specific stimulation parameters elicit certain sensations we must first understand the representation of those sensations in the brain. In this study we record from intracortical microelectrode arrays implanted in S1, premotor cortex, and posterior parietal cortex of a male human participant performing a somatosensory imagery task. The sensations imagined were those previously elicited by ICMS of S1, in the same array of the same participant. In both spike and local field potential recordings, features of the neural signal can be used to classify different imagined sensations. These features are shown to be stable over time. The sensorimotor cortices only encode the imagined sensation during the imagery task, while posterior parietal cortex encodes the sensations starting with cue presentation. These findings demonstrate that different aspects of the sensory experience can be individually decoded from intracortically recorded human neural signals across the cortical sensory network. Activity underlying these unique sensory representations may inform the stimulation parameters for precisely eliciting specific sensations via ICMS in future work.

Additional Information

© 2021 Bashford et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license, which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed. Received Sep. 19, 2020; revised Jan. 4, 2021; accepted Jan. 6, 2021. This work was supported by the National Institutes of Health National Institute of Neurological Disorders and Stroke Grant 5U01NS098975-02 (to L.B., I.R., S.K., K.P., D.K., B.L., C.L., and R.A.A.), the T&C Chen Brain-Machine Interface Center (L.B., I.R., S.K., K.P., and R.A.A.), the USC Neurorestoration Center (S.K., D.K., B.L., C.L.), the California Institute of Technology Biology and Biological Engineering Postdoctoral Fellowship (L.B.), and the James G. Boswell Foundation (R.A.A.). We thank the continued contribution from our study participant F.G. Author contributions: L.B., I.R., S.K., K.P., and R.A.A. designed research; L.B. and I.R. performed research; L.B., I.R., S.K., D.K., B.L., and C.L. contributed unpublished reagents/analytic tools; L.B. and I.R. analyzed data; L.B., I.R., S.K., and R.A.A. wrote the paper. The authors declare no competing financial interests.

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